SCARBOROUGH, Maine (AP) Maine’s growing number of COVID-19 cases is disproportionately affecting smaller towns.

The 20 ZIP codes with the highest infection rate in the last month are concentrated in York, Androscoggin, Kennebec and Oxford counties, and only three — Lewiston, Waterville and Sanford — are major urban areas, the Bangor Daily News reported.

Health officials said factors could be growing weariness of masks and social distancing.

The growth in infections comes even as the state’s vaccine effort ramps up. About 35% of Maine residents are fully vaccinated, and the vaccine is now available to everyone 16 and older.